Mequitazine (l), a phenothiazine quinuclidine derivative known for more than two decades exhibits potent antihistamine properties and is the active constituent of some pharmaceuticals. The previously described synthesis in a patent is not satisfactory, leading to poor yields.'The strategy involves the preparation of the 3-hydroxymethyl quinuclidine (6) which was condensed via its chloro derivative with phenothiazine. The original six-step ...